Paging Marc Haibeck: Cams

[Sgreg]

I noticed reading Marc's schedule of ZR-1 preformance mods, he does not recommend a Stage One cam change with fully ported 350 cube LT-5's. Just curious, is that because of cost /reward or ? Most tuners think a stage one treatment is worth 20-25 HP in a ported 350. Is that optimistic ? A couple of us are making that decision right now and don't need to spend more money if the reward isn't there.

[HAWAIIZR-1]

Greg,

Thanks for posting this question. Does Marc post on here? Excellent question as there are many different opinions from the different builders.

[rkreigh]

Originally Posted by Sgreg

I noticed reading Marc's schedule of ZR-1 preformance mods, he does not recommend a Stage One cam change with fully ported 350 cube LT-5's. Just curious, is that because of cost /reward or ? Most tuners think a stage one treatment is worth 20-25 HP in a ported 350. Is that optimistic ? A couple of us are making that decision right now and don't need to spend more money if the reward isn't there.

the FBI guys might have some thoughts on this one, Pete has done a TON of experimentation with cams on stock displacement and likely has the fastest stock bottom end car on the planet

no question you can pick up some HP with cams, even on stock displacement. how much, will vary depending on quite a few factors, porting, tuning, ect...

is it worth it? well, that depends on how "spendy" you are cams are expensive, and again, folks are working on new ones that might not be as bad but figure 1000-1500 PER cam (yikes!!)

look at the black widow and snake skinner projects. both used revised cam profiles I believe on the LT5 and picked up to 475 HP or so with the stock displacement

pete is well over that figure with more agressive porting and proper cam timing.

but it's clearly NOT cheap and should only really be considered when you are pulling the engine and porting the heads, tops end.

with the stock bottom end being rock solid, its a good way if you have "the means" to get more ponies

the amount will all depend on the full combination and getting the cam timing spot on to match the porting and tune

[Hammer]

Marc does not post to any of the forums as far as I know. Call him direct at 630-458-8427. I think it would be more appropriate to talk with him directly on this matter.

[XfireZ51]

I wonder if it wouldn't help to use the 93-95 cams in a ported 90-92.
It was my impression that cam profile was one if the reasons for the 405hp in the latter ZRs.

[Sgreg]

Originally Posted by XfireZ51

I wonder if it wouldn't help to use the 93-95 cams in a ported 90-92.
It was my impression that cam profile was one if the reasons for the 405hp in the latter ZRs.

Hmm, I thought the difference was primarily in the plenum porting changes from early to late models..

[Locobob]

Originally Posted by Sgreg

Hmm, I thought the difference was primarily in the plenum porting changes from early to late models..

It was a combination of things: revised cams, intake and exhaust manifolds.

[Ccmano]

Originally Posted by XfireZ51

I wonder if it wouldn't help to use the 93-95 cams in a ported 90-92.
It was my impression that cam profile was one if the reasons for the 405hp in the latter ZRs.

There's a 4 degree increase in valve overlap, lift and duration are the same. Most of the increase was due to the porting in the plenum, IH's and cylinder heads. Also the changes to the exhaust system.
H

[Pete]

I will not get into this with cams on an open forum i might get the boot some might think i'm bashing/insulting them.
Just compare for yourself.

Stock Cam Specs
Intake .214 .229 .390 .390
Exhaust .214 .214 .390 .390

Stage I Specs
Intake .228 .228 .415 .415
Exhaust .228 .228 .415 .415

Look and compare the two cam set up and tell me what's the differance,besides lift.

You can figure it out yourself.

Pete

[XfireZ51]

Originally Posted by Ccmano

There's a 4 degree increase in valve overlap, lift and duration are the same. Most of the increase was due to the porting in the plenum, IH's and cylinder heads. Also the changes to the exhaust system.
H

Hans,

Are you saying cam profile was the same, just LSA was tighter? It would make sense that if both ports are flowing equally, that you'd want same intake for both primary and secondary. Not sure about exhaust needing any help as I have heard it's pretty efficient already and then if you throw on headers...
You want to make certain you don't over-scavenge robbing power.

Pete,

Who would give you the boot over a discussion on cams?!